Re: [Leica] Time-line: focal length in centimeters versus millimeters on projection lenses, Epidiaskop IIIs

["Greg J. Lorenzo" <gregj.lorenzo@shaw.ca>]

Hi Willem,

Are you sure this thing's a Slide Projector?

It looks more like one of the Search Lights used by the Germans to find 
Allied bombers at night.

Regards,

Greg

Willem-Jan Markerink wrote:

>Dear group,
>
>Last week I became the proud owner of what must be one of the most 
>unique pieces of Leitz projection equipment, the Large Lecture Hall 
>Epidiascope IIIs[*]....a monstrous steel contraption, 211cm tall, 
>64cm wide, 94cm long, 300-500kg. Needed a full-size horsetrailer with 
>loading-ramp to haul it home, 5 men for pushing it in the trailer, 3 
>men for controlled unloading....8-))
>
>Here a preliminary image, lenses removed:
>
>http://www.a1.nl/phomepag/markerink/epimonst.jpg
>
>However, even though I bought it from the university where it had 
>been in active duty many many moons ago, it had been so long out of 
>duty, pushed aside in a projection room, only recently being forced 
>to move due to demolishing of the lecture hall itself, that no body 
>knew its year of build or purchase....it even preceeded the career of 
>the current janitor 
>("It's old Jim, but not as we know it...."....8-))
>
>My only time-line reference is the fact that I already had an 
>episcopic lens from another IIIs, with different focal length 
>annotation; 1:3.5/700mm instead of f=100cm/1:3.5 (both 'EPIS', and 
>yes, that's 20cm & 30cm lens diameter....the big one is too heavy to 
>lift to chest-height(!)).
>Can anyone tell me whether this helps putting a date stamp on it, at 
>least accurate to a margin of a decade?
>
>Serial number of the projector itself is A87052, but I doubt that 
>helps anything, unless a few known samples around this number exist.
>
>Oh, diascopic projection (up to 4x5", wooden slide-adapters of 
>14x14cm) is 110v/1500W (E40 lamp), episcopic projection is 4x 1500W 
>(with lens/condensor between lamp and paper, each lamp one lens, 
>never seen that in smaller episcopes; probably a must in large 
>lecture halls because of the highly inefficient nature of the 
>episcopic projection (reflective)). Episcope lenses are 50cm/1:5.7 
>and 60cm/1:4.5, in a dual/revolver set-up (for slightly different 
>formats of slides)....same lenses are used on smaller Diaskop and 
>Epidiaskop.
>
>[*] have yet to find the official German name, did speak to Leitz 
>folks on the PhotoKina, who agreed with my 'Grossraum Epidiaskop 
>IIIs' translation....further cooperative research is pending, as 
>hardly anyone working at Leitz today knows much about any 
>(Epi)Diaskop....either they are able to trace down one or more 
>senior/retired employees, or I might get an invitation to do research 
>in the Leitz archives itself....ah, the honor!....:))
>
>See also....
>
>http://www.a1.nl/phomepag/markerink/epimonst.htm
>
>....for the only picture from a IIIs I have found in Leitz literature 
>thusfar (this one has a 130cm episcope lens, 70cm diascope lens, but 
>with 'internal' focus, unlike the 'open' screw-collar of both my 
>700mm and 100cm episcope lens (and both diascope lenses as 
>well....only on an older & smaller Epidiaskop I have such 
>sliding/internal focussing lenses)  
>
>Only one time before have I seen such a IIIs projector being traded, 
>in the UK (within some kind of association of historical photography, 
>tried to track down more info back then, but failed due to their 
>shielded membership structure (internal auction)).
>
>More about the last range of 'smaller' Diaskop and Epidiaskop (until 
>late 60's) on:
>
>http://www.a1.nl/phomepag/markerink/diaskop.htm
>http://www.a1.nl/phomepag/markerink/epidiask.htm
>
>Bottom line:
>If *anyone* knows more about *any* of these projectors, in particular 
>this huge IIIs, please step forward, in the name of optical/academic 
>history....;))
>
>--                 
>Bye,
>
>Willem-Jan Markerink
>
>      The desire to understand 
>is sometimes far less intelligent than
>     the inability to understand
>
><w.j.markerink@a1.nl>
>[note: 'a-one' & 'en-el'!]
>
>
>--
>To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html
>



- --
To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html